Electrochemical drilling apparatus

ABSTRACT

A fixture for holding a workpiece during an electrochemical drilling operation which is loaded by a mechanism that properly locates the workpiece in the fixture.

Aug. 6, 1914 R N WS 3,827,965

ELECTROCHEMICAL DRILLING APPARATUS Filed Feb. 2, 1973 v 2 Sheets-'Sfiet 1 M W 2 0 g5 o v (6 k\ :"7 I R [f G /////////,/r-. ==1

A118. 1974 R. ANDREWS 3,827,965

ELECTROCHEMICAL DRILLING APPARATUS Filed Feb. 2, 1973 2 Sheets-Sheet 2 United States Patent 3,827,965 ELECTROCHEMICAL DRILLING APPARATUS Laurance R. Andrews, Agawam, Mass., assignor to United Aircraft Corporation, East Hartford, Conn.

Filed Feb. 2, 1973, Ser. No. 328,997 Int. Cl. B23p 1/02 U.S. or. 204-291 R Claims ABSTRACT OF THE DISCLOSURE A fixture for holding a workpiece during an electrochemical drilling operation which is loaded by a mechanism that properly locates the workpiece in the fixture.

BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION One feature of the invention is a fixture in which the workpiece is precisely located with the fixture subsequently located in the electrochemical drilling machine. Another feature is the mechanism by which the workpiece will be located with the needed precision within the fixture.

According to the present invention, a locating mechanism has locating points for the fixture which points coincide in location with the locating points on the electrochemical drilling machine, and the mechanism also has precision locating elements by which the workpiece will be precisely located with respect to the fixture while the latter is securely mounted in the fixture. Since these 10- eating points on the mechanism are separate from the drilling operation and thus not subject to an electrolytic action, these points will be effective over a long period, and will not cover areas on the part that are to be drilled.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation of the mechanism and fixture in open position.

FIG. 2 is a view similar to FIG. 1 with the mechanism in closed position.

FIG. 3 is a front elevation of the structure of FIG. 1.

FIG. 4 is a plan view of the fixture in position on the base.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, the fixture 2 is adapted to be positioned in an eletcrochemical drilling machine as described, for example, in the copending application of Andrews, Ser. No. 302,993 filed Nov. 1, 1972 and having a common assignee with this application. This fixture indicates a base 4 having an end edge 6, FIGS. 2 and 3 and opposed side edges 8 and 10 all serving as locating surfaces, as well as a bottom surface 12. This fixture is positioned on the locating mechanism base 14 which has a flat top surface 16 engaged by the surface 12 and cleats 18 and 20 secured thereto. Each cleat 18 and 20 has a surface 22 and 24 engageable by the end surface 6 and surfaces 26 and 28 engageable by the side surfaces 8 and Patented Aug. 6, 1974 10, respectively. Clamps 30 and 32 hold the fixture base in position. It will be understood that the electrochemical drilling machine will have locating means thereon'corresponding to the cleats 18 and 20.

The fixture base has two cups 34 and 36 thereon-which receive portions of the workpiece 38, as for example, the shroud ends 40 and 42 on the turbine vane which-is shown as the workpiece. The latter has an airfoil-portion 44 between the shroud ends and this airfoil portion is to have a plurality of holes 46 drilled in the trailing edge 48 thereof as shown by way of example in FIG. 2. It will be understood that these holes are shown by way of example and that such holes do not exist until this fixture with the vane thereon has been positioned in the drilling machine for the drilling operation.

The shroud ends are positioned in the cups and held securely therein by a suitable wax, or bedding compound 50, FIG. 3 which may be of any suitable self-hardening device that may subsequently be removed readily from the shrouds.

For a precision location of the vane in relation to the fixture, the locating mechanism base 14 has a post 52 thereon on which is pivotally mounted a bracket 54 as by a pivot bolt 56. The bracket 54 includes a post 58 engaged by the pivot 56, a locating sub-base 60, and a clamp carrying arm 62. The sub-base has a pair of spaced locating pins 64 and 66 for engaging the trailing edge of the airfoil portion of the vane at spaced points as shown. A supporting and locating stud 68 engages the vane along its convex surface for further precision location of the vane.

The arm 62 carries a clamping arm 70 on a pin 71 having a clamp shoe 85 engaging the leading edge of the vane about midway of its length as shown in FIG. 3 and this arm is clamped in position by a toggle linkage including a linkage arm 72 pivotally mounted on a pin 74 on a block 76 on the arm 62. This linkage arm 72 has a short actuating link 78 pivoted thereto by a pin 80 and pivoted on clamping arm 70 by a pin 82. A stop 84 limits the movement of arm 72 beyond the optimum clamping position shown to assure the workpiece 38 is firmly contacting locators 64, 66, 68 and '86.

The bracket 54 has a post 88 thereon in a position to engage the base 14 and support the bracket in the open position of FIG. 1. When the bracket is moved into the closed position of FIG. 2, the edge of the bracket 54 en- 'gages a fixed stop so that the locating sub-base 60 is held in precisely the position to locate the vane in the exact relation to the locating surfaces on the fixturebase.

When the mechanism is in the closed position of FIG. 2, the appropriate bedding compound is placed in the cups and the fixture remains in this position until the compound has solidified. Then, by releasing the clamping arm 72, the bracket is free to move out of the way of the fixture and the latter may be released from the clamps 30 and 32. This fixture may then be placed in the electrochemical drilling machine for a drilling operation, being located therein by the same locating surfaces used in the locating mechanism. In this way the trailing edge of the vane will be in the exact position for a drilling operation by the electrodes of the drilling machine. It will be noted that the fixture base has the locating surfaces 8 and 10 substantially at right angles to surface 6 and all of these surfaces are substantially at right angles to the bottom surface 12- locators do not cover areas on the part that are to be drilled.

Lc1ai.n1 .i s .l t

1. A fixture for locating a workpiece having spaced end elements by which the workpiece is to be held, said fixture 1 di a=- a baseha'ving aplurality of locating surfaces thereon by whichthe fixture is located on a machine tool,

a plurality of cups on said base spaced apart to receive 1 portionsof saidend elementsand in precise relation to-th elocating surfaces, and

l -a beddingcompound in said cups in which a portion of the end elements are embedded.

-- 2. A fixture as in claim 1- in which the base has at least three locating surfaces substantially at right angles to one another.

3. A fixture as in claim 1 in which the workpiece has an airfoil portion with a trailing edge and this trailing edge -,is precisely located with respect to said locating surfaces.

4. A locating mechanism for precision location of a workpiece in a fixture including:

a base having a plurality of locating surfaces for cooperation with similar surfaces on the fixture,

a pivoted member having workpiece locating elements thereon and a workpiece clamping device said member having a loading position in which the workpiece is placed in the clamping device and a locating position, and

a means for locating the pivoted member in locating position such that the locating elements are in precise relation to said locating surfaces, whereby a workpiece clamped in said member will be in precise relation to said locating surfaces. 5. A mechanism as in claim 4 in which the workpiece is a turbine vane having an airfoil portion with a shroud at each end and the locating elements are positioned to engage the trailing edge of the airfoil portion at spaced points.

6. A mechanism as in claim 5 in which the clamping device engages the leading edge of the airfoil portion of the vane near its mid-portion.

7. A locating mechanism for the precision location of a workpiece in a fixture said workpiece having spaced end elements by which the workpiece is held, the mechanism is positioned in the clamping device and a locating position, and

a means for locating the pivoted member such that in locating position the locating elements are in precise relation to said locating surfaces, whereby a workpiece clamped in said member will be in precise relation to said locating surfaces,

in combination with the fixture, the latter having a base having a plurality of locating surfaces cooperating with the surfaces on the mechanism base,

a plurality of spaced cups on the base of the fixture to receive the end elements of the workpiece, and

a bedding compound in said cups in which the end elements are embedded and held therein by the solidification of the bedding compound.

8. A device as in claim 7 in which the base of the locating mechanism has clamps to engage and hold the fixture in position.

9. A device as in claim 8 in which the fixture is releas ably positioned in the mechanism and is adapted to be similarly located in a machine with the workpiece thereon.

10. A device as in claim 7 in which:

the workpiece has an airfoil portion with end shrouds,

and with the airfoil portion in engagement with the locating elements and the clamping device and in which the workpiece is held in said fixture by end portions of the shrouds embedded in the bedding compound in the cups in such a position that the trailing edge of the airfoil portion is in precise relation to the locating surfaces on the fixture base.

References Cited UNITED STATES PATENTS 3,338,807 8/1967 Clifford 204-ECM Dig. 3,287,245 11/ 1966- Williams 204-224 M 3,311,549 3/1967 Bruns 204224 M 3,466,235 9/1969 Williams 204129.25 3,5 36,603 10/ 1970 Bonga 204224 M FOREIGN PATENTS 733,484 5/1966 Canada 204-ECM Dig. 1,066,197 4/ 1967 Great Britain 204ECM Dig.

FREDERICK C. EDMUNDSON, Primary Examiner US. Cl. X.R. 204-12925, 224 M 

